Expandable Tubular Centralizer

ABSTRACT

A centralizer device that is set by expansion of an inner expandable tubular member. The centralizer is made up of either one or a plurality of centralizer bands which radially surround an inner, radially expandable tubular member. Each of the centralizer bands includes one or more expansion sections which buckles under tension to form a loop. Generally semicircular, opposing tension straps are affixed to opposite end portions of the expansion section. The tension straps underlie the expansion section and radially surround the inner tubular member in a close-fitting, snug relation. A closure mechanism is used to secure each centralizer band to the inner tubular member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to centralizer devices that are usedwith expandable tubular members.

2. Description of the Related Art

During drilling, production or other operations within a borehole, it isoften desired to utilize a device for stabilizing or centralizing a toolstring within the borehole. Often, centralizers are constructed ofrib-like springs that bow outwardly from the tool string.

A centralizer device that can be used with a radially expandable tubularis described in U.S. Pat. No. 7,140,431.

SUMMARY OF THE INVENTION

The present invention provides a centralizer device for use with aninner radially expandable tubular member. The centralizer can be movedbetween a first, unset condition and a second, set condition. Thecentralizer is set by expansion of the inner expandable tubular member.In one described embodiment, the centralizer is made up of a pluralityof centralizer bands which radially surround the inner, radiallyexpandable tubular member. Each of the centralizer bands includes anexpansion section which can be buckled to form a loop. Generallysemicircular tension straps are affixed to opposite end portions of theexpansion section. The tension straps underlie the expansion section andradially surround the inner tubular member in a close-fitting, snugrelation. A closure mechanism is used to secure each centralizer band tothe inner tubular member. In an alternate embodiment, the centralizer isa single band having multiple expansion sections.

To move the centralizer to a set condition, the inner tubular member isradially expanded which exerts tension on the tension straps. Theexpansion sections of each centralizer band buckle and are bent into aradially protruding loop. The loop formed by each expansion section willcontact the interior radial surface of a surrounding tubular member andretaining the inner tubular member in a spaced relation away from theouter tubular member.

Either a single band or a plurality of centralizer bands are used tomake up the centralizer. In a described embodiment, each of thecentralizer bands is oriented such that its expansion section isradially offset from the expansion sections of the other centralizerbands. Preferably, the expansion sections of the centralizer bands areangularly spaced apart from one another using generally equal spacing,thereby ensuring that the inner tubular member will be generallycentered within the outer tubular member when the centralizer is set.

Devices constructed in accordance with the present invention permit aradially expandable tubular member to be centralized within an outertubular member according to methods of the present invention. Inaccordance with methods of the present invention, a centralizer device,formed of one or more centralizer bands, is disposed about thecircumference of the expandable tubular member. Thereafter, theexpandable tubular member and centralizer device are disposed within anouter tubular member. The expandable tubular member is then radiallyexpanded, causing the centralizer to move from the unset condition tothe set condition. When the centralizer device is in the set condition,the expandable tubular member is centralized within the outer tubularmember by contact between the loops formed by the expansion section(s)of the one or more centralizer bands and the surrounding outer tubularmember.

BRIEF DESCRIPTION OF THE DRAWINGS

For a thorough understanding of the present invention, reference is madeto the following detailed description of the preferred embodiments,taken in conjunction with the accompanying drawings, wherein likereference numerals designate like or similar elements throughout theseveral figures of the drawings and wherein:

FIG. 1 is an external, isometric view of an exemplary centralizer, inaccordance with the present invention, which is surrounding a radiallyexpandable inner tubular member and in a pre-expansion condition.

FIG. 2 is an external, isometric view of the centralizer and innertubular member of FIG. 1, now with the tubular member in a radiallyexpanded condition.

FIG. 3 is an axial cross-sectional view of an exemplary centralizer andinner tubular member in a pre-expansion condition and within an outertubular member.

FIG. 4 is an axial cross-sectional view of the centralizer and innertubular member of FIG. 3, now with the inner tubular member having beenradially expanded.

FIG. 5 is an external, isometric view of a single exemplary centralizerband.

FIG. 6 is a further external, isometric view of the centralizer bandshown in FIG. 5.

FIGS. 7-9 are detail views of the centralizer band shown in FIGS. 5 and6 depicting aspects of the centralizer band in its unset condition.

FIG. 8A illustrates an exemplary hinge type connection used with acentralizer band.

FIG. 10 is an external, isometric view of the centralizer band shown inFIGS. 5-9, now in a set condition.

FIGS. 11 and 12 are further external, isometric views of the centralizerband shown in FIGS. 5-9, now in a set condition.

FIG. 13 illustrates an alternative embodiment for a centralizerconstructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-12 depict an exemplary centralizer, generally indicated at 10,disposed upon an expandable inner tubular member 12 which presents anouter radial surface and which has a circumference. In embodiments, theinner tubular member 12 may comprise a production tubing string or anexpandable liner, of a type known in the art. The centralizer 10 is madeup of at least one, but preferably a plurality of, centralizer bands 14,16, 18, 20, 22 and 24 which radially encircle the tubular member 12 inpreferably a close fitting, snug relation, so that the centralizer bandsdo not easily slide or rotate their positions upon the outer radialsurface of the tubular member 12.

In the depicted embodiment, the centralizer bands 14, 16, 18, 20, 22 and24 each have an identical construction. FIGS. 5-12 illustrate anexemplary centralizer band 14 apart from the other components of thecentralizer 10. The exemplary centralizer band 14 includes a generallyrectangular, arcuately curved expansion section 26 that can beselectively buckled to be expanded radially outwardly. First, generallysemicircular tension bands 28, 30 underlie the expansion section 26. Thetension bands 28, 30 are affixed to one arcuate end 32 of the expansionsection 26. Preferably, as depicted best in FIG. 7, the tension bands28, 30 are extensions of the material forming the expansion section 26and are folded under the expansion section 26 at folds 34. As analternative to folding extensions of the material forming the extensionsection 26 under the expansion section 26, the tension bands 28, 30might be formed by affixing the tension bands 28, 30 to the arcuate end32 of the expansion section 26 using pins or other connectors of a typeknown in the art. It is noted that, while there are two, paralleltension bands 28, 30 shown affixed to the arcuate end 32 of theexpansion section 26, there might be more or fewer than two. However, atleast one tension band is affixed to the arcuate end 32. The tensionbands 28, extend about the circumference of the inner tubular member 12.

Another tension band 36 is affixed to an opposite arcuate end 38 of theexpansion section 26. In one embodiment, best seen in FIG. 8, thetension band 36 is an extension of the material forming the expansionsection 26 and is folded under the expansion section 26 at fold 40. Inan alternative embodiment, shown in FIG. 8A, the tension band 36 isaffixed by a hinge 37 to the arcuate end 38 of the expansion section 26.The hinge 37 may resemble a standard door hinge and receive hinge pin39. This method of attachment readily permits the expansion section 26to be fashioned from a different material than that making up thetension band 36. For example, the expansion section 26 might be formedof fiberglass while the tension band 36 is formed of sheet metal.

As best seen in FIG. 7, the tension band 36 preferably resides betweenthe two tension bands 28, 30. The exemplary tension bands 28, 30 may bethought of as a first tension band that is affixed to a first arcuateend 32 of the expansion section 26. The tension band 36 may be thoughtof as a second tension band, which is affixed to a second arcuate end 38of the expansion section 26 and which opposes the first tension band.

An exemplary closure mechanism 42 for the centralizer band 14 isillustrated in FIG. 9. In the depicted closure mechanism 42, endportions of each tension band 28, 30, 36 are curved and folded to formpin retainer portions 44 which align with one another. A pin 46 is thenremovably inserted into the pin retainer portions 44. In order to securethe centralizer band 14 around the inner tubular member 12, the pin 46is removed from the pin retainer portions 44 and the centralizer band 14is then placed to surround the inner tubular 12. The pin retainerportions 44 are then aligned with one another, and the pin 46 isinserted into the pin retainer portions 44. Preferably, multiplecentralizer bands are disposed around the inner tubular member 12 withthe expansion portions 26 of the various centralizer bands beingradially offset from one another about the circumference of the innertubular member 12. This permits the centralizer to provide roughly evencentralization and spacing from a surrounding tubular member. In theexample depicted in FIGS. 1-4, there are six centralizer bands 14, 16,18, 20, 22 and 24, each of which having its expansion section 26disposed in a generally equally angularly spaced relation to one anotherabout the circumference of the inner tubular member 12 (i.e.,approximately 60 degrees apart).

The centralizer 10 is actuated from its unset position (FIGS. 1, 3 and5-8) to its set position (FIGS. 2, 4, and 10-12) as the inner tubularmember 12 is radially expanded from an unexpanded condition (see FIG. 1)to a radially expanded condition (see FIG. 2). The inner tubular member12 may be expanded radially outwardly by fluid pressure or by mechanicalswaging or by other techniques known in the art. As the inner tubularmember 12 expands radially, the tension bands 28, 30 are placed intension against the tension band 36. The arcuate end 32 of the expansionsection 26 is urged closer to the second arcuate end 38. The expansionsection 26 of each centralizer band 14, 16, 18, 20, 22, 24 buckle andform a loop that expands as the inner tubular member 12 expands furthereventually contacting the interior radial surface 48 of a surroundingouter tubular member 50. See FIG. 4. The expansion sections 26 retainthe inner tubular member 12 in a spaced relation from the outer tubularmember 50, thereby centralizing the inner tubular member 12 within theouter tubular member 50.

The components of the centralizer bands 14, 16, 18, 20, 22 and 24 may beformed from materials that are capable of transmitting significanttension through the tension bands 28, 30, 36 and which permit theexpansion section 26 to deform into a loop, as described. In currentlypreferred embodiments, the centralizer bands 14, 16, 18, 20, 22 and 24are made of sheet metal. However, other suitable materials may also beused.

FIG. 13 illustrates an alternative centralizer 10′ which has beenconstructed in accordance with the present invention. In FIG. 13, thecentralizer 10′ is depicted in an unrolled fashion and apart from atubular member 12. The centralizer 10′ includes four expansion sections26 which are depicted in an unset state. The expansion sections 26 areinterconnected with one another by tension bands 28, 30 and 36. It isnoted that, while four expansion sections 26 are shown, there may bemore or fewer than four, if desired. It is currently preferred thatthere be roughly equivalent spacing between expansion sections 26 sothat when affixed to an expandable tubular member and moved to the setposition, the expanded sections 26 will have a substantially equalangular spacing about the circumference of the tubular member. The ends52, 54 of the centralizer 10′ may be joined to each other with the useof pins or other connectors, as are known in the art. It is noted thatthe use of multiple expansion sections 26 on a single centralizer bandeliminates having to adjust the angular orientation of expansionsections 26 of multiple centralizer bands, such as 14, 16, 18, 20, 22and 24.

The present invention also provides inventive methods for centralizingan inner expandable tubular member 12 within a surrounding outer tubularmember 50. In an exemplary method, a centralizer, made up of one or morecentralizer bands 14, 16, 18, 20, 22 and/or 24, is disposed around thecircumference of the inner expandable tubular member 12. The innerexpandable tubular member 12 is in an unexpanded condition, and thecentralizer bands 14, 16, 18, 20, 22 and/or 24 are in an unset conditionat this time. Preferably, the centralizer bands 14, 16, 18, 20, 22and/or 24 are secured around the inner tubular member 12 in a snug,close-fitting relation. Preferably also, the centralizer bands 14, 16,18, 20, 22 and/or 24 are so secured by fastening the closure mechanism42 of each of the centralizer bands 14, 16, 18, 20, 22 and/or 24, asdescribed previously.

The inner tubular member 12 and affixed centralizer 10 are thereafterdisposed within the outer tubular member 50 (see FIG. 3). Next, theinner tubular member 12 is radially expanded from the unexpandedcondition depicted in FIGS. 1 and 3 to the radially expanded conditionshown in FIGS. 2 and 4. As the inner tubular member 12 is radiallyexpanded, the centralizer bands 14, 16, 18, 20, 22 and/or 24 are movedfrom their unset condition to their set condition. Radial expansion ofthe inner tubular member 12 causes the first tension bands 28, 30 toexert tension on the first arcuate end 32 of the expansion section 26,while the second tension band 36 exerts tension on the second arcuateend 38 of the expansion section 26. As a result, the arcuate ends 32, 38are urged closer toward each other causing the expansion section 26 tobuckle and form a loop. The loop of the expansion section 26 for eachcentralizer band 14, 16, 18, 20, 22 and/or 24 will contact the outertubular member 50 to centralize the inner tubular member 12 within theouter tubular member 50.

Those of skill in the art will recognize that numerous modifications andchanges may be made to the exemplary designs and embodiments describedherein and that the invention is limited only by the claims that followand any equivalents thereof.

1. A centralizer for a radially expandable tubular member having anouter radial surface with a circumference, the centralizer comprising: acentralizer band which radially surrounds the expandable tubular memberand comprises: an arcuate expansion section overlying a portion of theouter radial surface of the expandable tubular member, the expansionsection having first and second arcuate ends and being deformable into aloop as the first and second arcuate ends are moved toward each other; afirst, generally semi-circular tension band affixed to the first arcuateend and extending about a portion of the circumference of the expandabletubular member; a second tension band affixed to the second arcuate endand extending about a portion of the circumference of the expandabletubular member; and the first and second tension bands being secured toeach other.
 2. The centralizer of claim 1 wherein there is a pluralityof centralizer bands forming the centralizer.
 3. The centralizer ofclaim 2 wherein the expansion section of each of the plurality ofcentralizer bands is angularly offset from the expansion sections ofother centralizer bands.
 4. The centralizer of claim 3 wherein theexpansion sections of the centralizer bands are generally equallyangularly spaced relative to one another about the circumference of theexpandable tubular member.
 5. The centralizer of claim 1 wherein thereis a single centralizer band having multiple expansion sections.
 6. Thecentralizer of claim 1 wherein: expansion of the expandable tubularmember moves the centralizer from an unset condition, wherein theexpansion section of the centralizer band is not deformed into a loop,to a set condition wherein the expansion section is deformed into aloop.
 7. The centralizer of claim 1 wherein the centralizer band issubstantially formed of sheet metal.
 8. The centralizer of claim 1further comprising a closure mechanism for securing the first tensionband to the second tension band, the closure mechanism comprising: pinretainer portions formed in each of the first and second tension bands;and a retaining pin that is secured within the pin retainer portions. 9.The centralizer of claim 1 wherein at least one of the first and secondtension bands is affixed to the expansion section by a hinge.
 10. Acentralizer for a radially expandable tubular member having an outerradial surface with a circumference, the centralizer comprising: acentralizer band, said centralizer band radially surrounding theexpandable tubular member and comprising: an arcuate expansion sectionoverlying a portion of the outer radial surface of the expandabletubular member, the expansion section having first and second arcuateends and being deformable into a loop as the first and second arcuateends are moved toward each other; a first, generally semi-circulartension band affixed to the first arcuate end and extending about aportion of the circumference of the expandable tubular member; a secondtension band affixed to the second arcuate end and extending about aportion of the circumference of the expandable tubular member; the firstand second tension bands being secured to each other; and whereinexpansion of the expandable tubular member moves the centralizer from anunset condition, wherein the expansion section of the centralizer bandis not deformed into a loop, to a set condition wherein the expansionsection is deformed into a loop.
 11. The centralizer of claim 10 whereinthere is a plurality of centralizer bands forming the centralizer. 12.The centralizer of claim 11 wherein the expansion section of each of theplurality of centralizer bands is angularly offset from the expansionsections of other centralizer bands.
 13. The centralizer of claim 12wherein the expansion sections of the centralizer bands are generallyequally angularly spaced relative to one another about the circumferenceof the expandable tubular member.
 14. The centralizer of claim 11wherein there are six centralizer bands forming the centralizer.
 15. Thecentralizer of claim 10 wherein the centralizer band has multipleexpansion sections.
 16. The centralizer of claim 10 further comprising aclosure mechanism for securing the first tension band to the secondtension band, the closure mechanism comprising: pin retainer portionsformed in each of the first and second tension bands; and a retainingpin that is secured within the pin retainer portions.
 17. Thecentralizer of claim 10 wherein at least one of the first and secondtension bands is affixed to the expansion section by a hinge.
 18. Amethod for centralizing an inner, radially expandable tubular memberwithin an outer tubular member, the method comprising the steps of:disposing a centralizer around the inner tubular member, the centralizercomprising at least one centralizer band having: an arcuate expansionsection having first and second arcuate ends and being deformable into aloop as the first and second arcuate ends are moved toward each other; afirst, generally semi-circular tension band affixed to the first arcuateend and extending about a portion of the circumference of the innerexpandable tubular member; a second tension band affixed to the secondarcuate end and extending about a portion of the circumference of theinner tubular member; disposing the inner tubular member and thecentralizer within an outer tubular member; and radially expanding theinner expandable tubular member, the radial expansion causing thecentralizer bands to move from an unset condition to a set condition,thereby centralizing the inner tubular member within the outer tubularmember.
 19. The method of claim 18 wherein the at least one centralizerband is moved from the unset to the set condition by: the first andsecond tension bands exerting tension upon arcuate ends of eachexpansion section to cause the expansion section to buckle and form aloop.
 20. The method of claim 18 wherein the step of disposing acentralizer around the inner tubular member further comprises: disposingmultiple centralizer bands around the inner tubular member such that theexpansion sections of each centralizer band is angularly offset from theexpansion sections of other centralizer bands.
 21. The method of claim20 wherein the expansion sections of the centralizer bands are generallyequally angularly spaced relative to one another about the circumferenceof the inner tubular member.
 22. The method of claim 18 wherein the stepof disposing the centralizer around the inner tubular member furthercomprises securing the at least one centralizer band by fastening aclosure mechanism.
 23. The method of claim 18 wherein the step ofdisposing a centralizer around the inner tubular member furthercomprises: disposing a centralizer band with multiple expansion sectionsaround the inner tubular member.